In a wireless network, a wireless device may communicate with one or more radio network nodes to transmit and receive voice traffic, data traffic, control signals, and so on. Maintaining good signal quality between the wireless device and the radio network node may allow for good performance, such as high bitrate transmissions or robust control channel performance. However, it may be difficult to maintain good signal quality in complex radio environments.
For example, to meet higher capacity demands and to enhance user experience, cellular communications networks are increasing the number of base stations employed. One approach for increasing the density of base station is achieved by splitting macro cells in highly loaded geographical areas into multiple smaller cells. Another approach is to employ a heterogeneous network that includes a mixture of macro cells and small cells with overlapping coverage areas within the cellular network. One example includes a cellular network having clusters of pico cells within the macro coverage area to offload macro traffic. A pico base station provides service to a pico cell. Typically, a pico base station is a low power node (LPN) that transmits with low output power and covers a much smaller geographical area than a high power node, such as a macro base station. Other examples of low power nodes are home base stations and relays.
The densification of the underlying support for the cellular network may allow radio resources to be reused. Additionally, because wireless devices may be closer to the serving base station, wireless devices may achieve higher bitrates. However, though the presence of additional base stations increases system performance and improves user experiences, such networks are not without its disadvantages. For example, interfering cells may create noise that interferes with the signal quality.
To mitigate inter-cell interference, mitigation techniques have been employed on the transmitter side, the receiver side, or on both sides. Interference mitigation on the transmitter side includes those methods that seek to coordinate the physical channel transmissions across cells to avoid severe interference. For example, an aggressor base station may occasionally mute its transmissions on certain radio resources in order for a victim base station to schedule interference sensitive wireless devices on radio resources with reduced interference. On the receiver side, advanced receivers may employ enhanced interference suppression schemes, maximum likelihood techniques, and/or interference cancellation techniques. Application of these advanced interference cancellation techniques to signals originating from other cells requires blind estimation of certain signal format parameters. Currently no signaling is defined in long term evolution (LTE) standard in order to provide wireless devices with the assistance which may be needed in order to implement advanced receivers with limited complexity.